Does spacelike separation have anything to do with non-locality?

The cause-effect relationship of timelike events is fairly self-evident.

But I was wondering, do non-local effects of QM "synchronise" events that are separated along spacelike intervals? Could there be some kind of co-dependent arising, such that if event X happens in one region of the universe then event Y will certainly happen in a spacelike separated region?

There would be no information transfer and neither event can be said to have caused the other, because obviously what caused X is what caused X and what caused Y is what caused Y. But all things come from t=0, meaning they could be fundamentally synchronised by virtue of the behaviour of spacetime in its early days.

If things like ADS/CFT have any bearing on reality, then surely spacelike separated events aren't quite as separated as we think they are? Rather they would be perfectly coincidental.

I have an intuition that what we think are "black holes" are actually just the "edges"/"corners" of the universe reflecting information back out. These "edges" exist dynamically in relation to spacetime geometry, explaining why they appear and disappear at convenient points.

That is to say, a 4D white hole and black hole pair form in a higher dimensional space.

Because they are pair produced, they exist in perfect equilibrium at t=0. No quantum fluctuations.

They would interact with their surroundings but the white hole would feed the black hole (us) so the black hole gets bigger and bigger. This would produce the appearance of inflation. When it gets to a tipping point, the white hole is now the black hole and the black hole is now the white hole, they become one "bubble" in the multiverse. At this point, the bubble is formed and can no longer be causally affected by fluctuations in the rest of the multiverse.

That would manifest as the "surface of last scattering"/the end of inflation. This would give off the appearance of a standalone 4D universe which has an "imprint" proportioning everything (the original quantum fluctuations imaged by the horizon).

Everything is rapidly moving away from us, faster and faster. Somewhere along the line there will be a point of no return. The time at which this point occured depending on the geometry of our sphere of observation relative to the universe at large. The stars will fade into what we percieve as nothing. All that would remain is the causal trace of all the information present at the precise boundary where the acceleration finally overwhelmed the information supply. In the local geocentric universe, there will be just Earth, if it's still around as Earth and that would perhaps soon be ripped apart too depending on spacetime geometry at that point.

The cause-effect relationship of timelike events is fairly self-evident.

But I was wondering, do non-local effects of QM "synchronise" events that are separated along spacelike intervals? Could there be some kind of co-dependent arising, such that if event X happens in one region of the universe then event Y will certainly happen in a spacelike separated region?

Nope. Quantum mechanics is fully-local. It has some effect which appear to be non-local, but all of the dynamics are fully local.